Remove PhabricatorRepository::loadAllByPHIDOrCallsign()

Summary: Ref T603. Move to real Query classes.

Test Plan:
  - Ran `phd debug pull X` (where `X` does not match a repository).
  - Ran `phd debug pull Y` (where `Y` does match a repository).
  - Ran `phd debug pull`.
  - Ran `repository pull`.
  - Ran `repository pull X`.
  - Ran `repository pull Y`.
  - Ran `repository discover`.
  - Ran `repository delete`.
  - Ran `grep`.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7137
Add viewPolicy, editPolicy, repositoryPHID columns to DifferentialRevision

Summary: Ref T603. Paves the way for policy controls.

Test Plan: Ran storage upgrade, bumbled around in Differential.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7133
Use Differential policy columns to drive policies

Summary:
Ref T603. Read policies out of policy columns.

When a revision is associated with a repository (which is currently never), require view access on the repository to see the revision (or, require the viewer to be the owner). This is a blanket "do the right thing" rule which should make Differential's default policies align with user expectations.

Future diffs will populate the `repositoryPHID` when a revision is created.

Test Plan: Tooled around Differential. None of this stuff does anything yet, so nothing very exciting happened.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7134
Show policy information in Differential header

Summary: Ref T603. Moves policy information from a custom field to the header for revisions.

Test Plan: Looked at a revision.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7135
Make most Differential reads policy-aware

Summary: Ref T603. Makes the majority of reads policy aware (and pretty much all the important ones).

Test Plan:
  - Created a comment with `differential.createcomment`.
  - Created a new revision with `arc diff` in order to exercise `differential.creatediff`.
  - Created an inline comment with `differential.createinline`.
  - Added a comment to a revision.
  - Edited an inline comment.
  - Edited a revision.
  - Wrote "Depends on ..." in a summary, saved, verified link was created.
  - Browsed a file in Diffusion.
  - Got past the code I changed in the Releeph request thing.
  - Edited a Releeph request.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7136
Add storage and classes for CustomField in Differential

Summary: Ref T3886. Adds the storage, indexes, and storage classes for modernizing Differential custom fields.

Test Plan: Ran `storage upgrade`.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T3886

Differential Revision: https://secure.phabricator.com/D7138